The actual speed and severity of climate change might be much greater than what we are led to believe by current predictions, a new study says.
Reappraisal of the models used by climate scientists to determine future warming reveals that less optimistic estimates are more realistic.
In the light of the results, the Paris Climate Agreement, aimed at keeping global average temperatures from rising by 2°C, may be overly ambitious.
''Our study indicates that if emissions follow a commonly used business-as-usual scenario, there is a 93 per cent chance that global warming will exceed 4°C by the end of this century,'' said Dr Ken Caldeira, an atmospheric scientist at the Carnegie Institution for Science, who co-authored the new study, The Independent reported.
Climate models serve as important tools for scientists for evaluating the impacts of greenhouse-gas emissions. The models use fundamental knowledge of physics and the world's climate.
The climate system, is however incredibly complex, there is therefore much disagreement about how best to model its key aspects.
This means scientists have produced dozens of climate models that project a range of different global warming outcomes resulting from greenhouse-gas emissions.
On the basis of a ''business-as-usual'' scenario whereby emissions continue at the same rate, climate models range in their predictions from a 3.2°C increase in global temperatures to a 5.9°C increase.
The climate change simulations that best capture current planetary conditions are also the ones that predict the most dire levels of human-driven warming, according to a statistical study released in the journal Nature on Wednesday.
The study, conducted by Patrick Brown and Ken Caldeira of the Carnegie Institution for Science, examined the high-powered climate change simulations, or models, that researchers use to project the future of the planet on the basis of physical equations that govern the behaviour of the atmosphere and oceans.
The study adds to a growing body of bad news regarding the impact of human activity on the planet's climate and how dire those changes will be. However, according to several outside scientists consulted by The Washington Post, though the research is well executed and intriguing, it is not yet definitive.
"The study is interesting and concerning, but the details need more investigation," said Ben Sanderson, a climate expert at the National Center for Atmospheric Research in Boulder, Colorado.